The beta-adrenergic receptor from turkey erythrocyte membranes has been solubilized in deoxycholate retaining its function to activate an adenylate cyclase system. After removal of the detergent the receptor can be implanted in a foreign cell to activate its adenylate cyclase. This system will be used as an assay for the purification of a functional receptor. Such an approach seems essential since purification of hormone receptors reported thus far produced preparations which were not functional in reconstitution experiments. The guanyl nucleotide binding component of the adenylate cyclase system will also be monitored during purification with the aim of separating this latter component from the receptor. A purified preparation of a functional beta-adrenergic receptor seems essential for the study of its mode of action at the molecular level.